It is often desirable in a polymer-coating "surface" application that a thermoset coating composition possess not only relatively large "hardness" and "scratch resistance" values but also relatively large "degree-of-flexibility" and "impact resistance" values. Unfortunately, in the production of a typical "coatings" polymer of this type, some of the process parameters that control the physical properties of such a polymer seem to be undesirably linked. For example, when certain process variables are selectably controlled so as to produce a thermoset coating composition possessing certain acceptable or desirable hardness and scratch resistance values, such a polymer generally is found to possess little, if any, flexibility and impact resistance, which is of course undesirable and in some applications totally unacceptable. In contradistinction, a polymer that is so produced as to possess desirable flexibility and impact-resistance values typically also is found to possess an unacceptable hardness and/or scratch-resistance value. It is currently believed that conventional manufacturing processes and methods cause these physical properties to be so related.
Briefly, conventional manufacturing processes can be summarized as follows. Many polymeric thermoset coating compositions that can be utilized in a polymer-coatings application are typically produced from preselected monomers, utilizing a series of manufacturing steps. Specifically, and as an example, such a conventional polymer often comprises a main chain, and typically includes side chains appended to the main chain. The main chain and pendant side chains, in particular, are furthermore typically formed at different times via separate reaction mechanisms, often utilizing separate reaction equipment to produce the desired polymer product. U.S. Pat. Nos. 3,892,714 and 4,005,155, both to Sampson et al., disclose processes that are fairly typical of such a conventional reaction scheme.
However, from for example an engineering standpoint, from a capital-investment standpoint, from a manpower-utilization standpoint, from an equipment-scheduling standpoint, and from a product-manufacturing standpoint, it would be not only desirable but also economical to effect the main-chain as well as the side-chain formations of such a polymer via a single, i.e. one-step, reaction mechanism, if possible.
Furthermore, it is also fairly typical, in many of the known, conventional polymer coatings-manufacturing processes, to utilize a catalyst to effect the main-chain and/or the side-chain formation of the desired polymer product. See, in particular, U.S. Pat. Nos. 3,892,714 and 4,005,155, both to Sampson et al.
One disadvantage of utilizing a catalyst in conjunction with a one-step reaction mechanism is that the catalyst, which is typically utilized to effect the side-chain polymerization reaction, if also present when the main-chain polymerization reaction takes place, can undesirably interfere with the main-chain polymerization reaction. This, in turn, may result in the production of a polymer product having undesirable properties, or may result in the production of an undesirable polymerization by-product that needs to be separated from the desired polymer product.
The catalyst that is typically utilized to effect a particular side-chain polymerization reaction, moreover, may cause transesterification at the main-chain portion of the polymer, resulting in undesired crosslinking of certain portions of the thus-produced polymer product. Such a result is undesirable because such crosslinking tends to increase the viscosity of the thus-produced polymer product in its polymerization solvent, and may even result in the gellation of the polymer product (or products) thus produced, which is of course usually undesirable as well.
It would therefore further be desirable not only to be able to produce such polymer products via a one-step reaction mechanism but also to be able to produce such polymer products without requiring the presence of catalyst, which would otherwise be needed to effect desired side-chain polymerization.
We have discovered that a novel polymer product of this type (e.g. a "polyol" polymer) can be produced via a one-step polymerization-reaction process. Such a process utilizes, for example, a single reaction vessel, while the main chain and side chains of such a polymer product are being formed substantially simultaneously. That is, we have discovered a one-step polymerization reaction mechanism that involves at least two different polymerization reactions which take place --we believe--substantially simultaneously.
We have advantageously also discovered that this particular dual-reaction mechanism can proceed without need of catalyst, which might otherwise conventionally be required to effect the side-chain polymerization.
Surprisingly, we have further discovered, by selectively controlling certain variables of our process, that we thus are able to produce a novel polyol polymer which, in turn, can be utilized to produce certain polymeric thermoset coatings possessing not only relatively large "hardness" and "scratch resistance" values but which also possesses relatively large "degree-of-flexibility", "resiliency", and "impact resistance" values as well.